'An American engineering group developing an innovative, split-cycle version of the internal combustion engine is claiming a significant breakthrough in the engine's efficiency as a result of high pressure turbocharging. The Michigan-based Scuderi Group is developing a petrol engine in which the induction, compression, power and exhaust duties of a four stroke engine are shared across a pair of cylinders rather than one, to separate the piston's compression stroke from the power stroke. This arrangement reduces pumping losses, allows the spark to ignite the mixture after top-dead-centre to generate a more rapidly igniting flame and as a consequence, more power for a given quantity of fuel'.

Every time the price of petrol goes up, the silver bullets crawl out of their dark hiding places into the glare of the lights, where they shrivel up in the reality of massive development costs against at most marginal efficiency improvements.

Every time the price of petrol goes up, the silver bullets crawl out of their dark hiding places into the glare of the lights, where they shrivel up in the reality of massive development costs against at most marginal efficiency improvements.

This sounds like a more complicated, and expensive engine design.

Yes, it might work and make slightly better use of fuel, but as you and I have previously posted, you cant break the laws of physics, therefore any gains from new types of petrol engine will be limited._________________"Installers and owners of emergency diesels must assume that they will have to run for a week or more"

Yes, it might work and make slightly better use of fuel, but as you and I have previously posted, you cant break the laws of physics, therefore any gains from new types of petrol engine will be limited.

I'm not quite sure I agree with this.

A "small" hatchback can get 50mpg today, yet be bigger and faster than a family hatchback that got 20mpg 30 years ago.
The Tesla does 200 miles on a battery that stores much energy as a gallon of petrol.

Depsite the increasing size and weight of cars over the past 50 years, engine efficiency has grown faster._________________I'm a realist, not a hippie

Petrol engines have not improved that much in recent decades.
Better fuel consumption is only partly due to more efficient engines, reduced weight, more streamlined bodywork, electric cooling fans, and lower loses in the transmision system have played a significant part.
Even lower rolling resistance tyres save a little, a very small amount in % terms but worthwhile over the life of the tyres.

Additional improvements are likely but I would expect these to be limited for vehicles of more or less standard design.

Vehicle electrical systems may change to 42 volts, that should save fuel, but only a very little, not a step change._________________"Installers and owners of emergency diesels must assume that they will have to run for a week or more"

I know diesel engines made good progress by switching to high-pressure direct injection and forced induction, leaving petrol engines behind a bit, but there are some manufactures working on direct injection petrol engines with higher pressure fuel pumps and injectors, plus forced induction. Nissan is going to offer the new Micra with a 1.2 litre DI supercharged petrol engine later this year. 95 g/Km and free tax.

Agree with the above about not being able to change the laws of physics though.

The improvements in car engine design have been largely in improving the power to weight ratio of the engine and transmission. A lighter engine needs a lighter chassis and less powerful brakes etc. for the same performance, all other things being equal. Less weight means more fuel efficiency for acceleration. That makes a big difference in stop start driving.

However, the overall thermodynamic efficiency of the engine has not increased much. That is limited by the Carnot cycle. You need to increase the temperature of combustion or the compression ratio to do that, since the unburnt fuel has already been cut to effectively zero in modern designs.

Of course, most of the weight gains from the engine have been lost by bigger bodies and heavier crumble zones to improve crash performance.

Yes, it might work and make slightly better use of fuel, but as you and I have previously posted, you cant break the laws of physics, therefore any gains from new types of petrol engine will be limited.

I'm not quite sure I agree with this.

A "small" hatchback can get 50mpg today, yet be bigger and faster than a family hatchback that got 20mpg 30 years ago.
The Tesla does 200 miles on a battery that stores much energy as a gallon of petrol.

Depsite the increasing size and weight of cars over the past 50 years, engine efficiency has grown faster.

There's a thing called "the law of diminishing returns". The more you improve something the more it costs to improve it further and the smaller increment you get on what you improved previously. It's an upside down exponential curve._________________BLOG

It is very, very, very serious indeed. This is the big one!" Professor Tim Lang, APPGOPO, 25/03/08. And he was talking about food, not oil or the economy!

But overall, cars have been getting heavier have they not?
Even if the engine block has lost weight, its been more than compensated by the increased safety features and bigger vehicles.
Or so I thought._________________I'm a realist, not a hippie

This is still a complex design that requires more moving parts than a standard engine. Modern efficient engines are moving to fewer cylinders to cut costs. Direct control of valves and injectors removes the need for camshafts. My engine has 3 cylinders. The Fiat twin air has two.

The air compression hybrid design is a bit of an afterthought. It only has limited potential to recycle energy, which would make most savings in agressive stop - start driving, the style of driving we need to avoid.